page_title: TNNI1
section_title: Gene evolution
hierarchical_section_title: TNNI1 / Gene evolution
caption_attribution_description: English: Evolutionary lineage of vertebrate TNNI1 deduced from alignment of ssTnI amino acid sequences
context_page_description: Troponin I, slow skeletal muscle is a protein that in humans is encoded by the TNNI1 gene. It is a tissue-specific subtype of troponin I, which in turn is a part of the troponin complex.
  Gene TNNI1, troponin I type 1, also known as TNN1 and SSTNI, is located at 1q31.3 in the human chromosomal genome, encoding the slow twitch skeletal muscle isoform of troponin I, the inhibitory subunit of the troponin complex in striated muscle myofilaments. Human TNNI1 spans 12.5 kilobases in the genomic DNA and contains 9 exons and 8 introns. Exon 2 to exon 8 contain the coding sequences, encoding a protein of 21.7 kDa consisting of 187 amino acids including the first methionine with an isoelectric point of 9.59.
context_section_description: Three homologous genes have evolved in vertebrates, encoding three muscle type-specific isoforms of TnI. In mammals, the amino acid sequence of ssTnI is highly conserved. Mouse and bovine ssTnI each differs from human ssTnI in only four amino acids, and rhesus monkey ssTnI is identical to human in the amino acid sequences. In lower vertebrates, the divergence of ssTnI between species is larger than that in the higher vertebrates (Fig1).
caption: Figure 1: Evolutionary lineage of vertebrate TNNI1 deduced from alignment of ssTnI amino acid sequences.
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